You shouldn't be relying on the clipboard for long-term (or even short-term) storage of critical items. The clipboard is intended as a temporary holding place for items copied/cut until they're pasted into their destinations. If you want to find it, then you need to paste it into something else - like a note-taking app (I recommend Google Keep), or perhaps in an email that you send to yourself.
If you need additional help or have more questions or details to share, please join the site so you can reply in this thread. See this link for instructions on how to join Android Central.